Mr Lewis, who was put in charge of leading the capital's policy of youth crime, said he had stepped down in the face of an "avalanche" of allegations against him.

The Deputy Mayor faced multiple claims relating to his time as a priest and as founder of an academy for young people. An independent inquiry was launched in City Hall today into the allegations.

In a statement, Mr Lewis said the "drip, drip" of allegations was "getting in the way of the very important work of this Mayor and his vision for London".

He added that the inquiry announced yesterday by Boris Johnson had done "little to calm the avalanche of allegations".

He thanked Mr Johnson for giving the opportunity to serve London.

But he added: "I cannot allow the things that I have been into, up to and around me to obscure the important business of this mayoral team.

"For this reason I must step down as Deputy Mayor for young people with immediate effect."

He said Mr Johnson had "reluctantly accepted" the resignation.

Mr Lewis has denied the claims against him, describing them as "complete rubbish".

They relate to alleged inappropriate behaviour with a parishioner in the late 1990s and while at the Eastside Young Leaders Academy - a youth scheme founded by Mr Lewis in 2003, the Mayor's office confirmed.

Separate claims of financial irregularity centre on money entrusted to the deputy mayor while he was a priest.

It has been reported that in 1999, Mr Lewis was barred from working with the Church of England. Something the now former deputy mayor has said he was not aware of.

Mr Johnson entrusted Mr Lewis, a former priest and prison governor, with the brief of young people shortly after being elected.

Today's resignation is the second to damage Mr Johnson's team since he became mayor on 1 May.

Last month one of his senior advisers quit after apparently remarking that Caribbean immigrants should go home if they did not like London.

Mr Johnson insisted that James McGrath, his political adviser, was not a racist.

But the Mayor said it would only provide "ammunition" for his critics if Mr McGrath was to remain in his post.